/* ===== 全局重置 ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* ===== 每一屏占满整个视口 ===== */
.screen {
    height: 100vh;
    width: 100%;
    position: relative;
}

/* ===== 第一屏 ===== */
.screen-1 {
    background-image: url('../images/bg1.jpeg');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
}

/* ===== 第二屏 ===== */
.screen-2 {
    background-image: url('../images/bg2.jpeg');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
}

/* ===== 第三屏 ===== */
.screen-3 {
    background-image: url('../images/bg3.jpeg');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
}

/* ===== 按钮样式 ===== */
.btn {
    width: 400px;
    height: auto;
    cursor: pointer;
    position: absolute;
    left: 50%;
    top: 93%;
    transform: translate(-50%, -50%);
    background: transparent;
    filter: drop-shadow(0 8px 30px rgba(0, 0, 0, 0.5));
    transition: all 0.3s ease;
}

/* ===== 按钮悬停效果 ===== */
.btn:hover {
    transform: translate(-50%, -50%) translateY(-6px);
    filter: drop-shadow(0 14px 40px rgba(255, 100, 0, 0.5));
}